Dielectric barrier discharge lamp

Abstract: The invention relates to a dielectric barrier discharge lamp, in which a discharge vessel with a hollow cylindrical discharge space, which is designed so that an external tube as well as an internal tube with approximately cylindrical outer shapes are arranged coaxially to one another, is filled with a discharge gas forming "excimer" molecules by a dielectric barrier discharge, in which an outer wall of the external tube is at least partially transparent relative to the light radiated from the "excimer" molecules and at the same time also functions as a dielectric of the dielectric barrier discharge, and in which the light-transmitting dielectric is provided at least partially with electrodes, wherein a means for hermetic sealing of an interior of the internal tube is arranged. With the lamps of the invention, a contamination of the internal tube forming the hollow cylinder is prevented and thus lamps having a high reliability are obtained.

Description: The invention relates to a so-called dielectric barrier discharge lamp, which is used, for example, as an ultraviolet light source for a photochemical reaction, and in which light radiated from "excimer" molecules, which are formed by a dielectric barrier discharge, is used. Laid-open patent application EP-A-0 547 366, on which the preamble of claim 1 is based, describes a high performance radiator with two concentrically arranged tubes of cylindrical shape forming a discharge vessel where both ends of the tubes are covered with plates for sealing the discharge space and the interior of the inner tube. However, orifices are provided in both plates to allow, for purposes of cooling and dielectric coupling, a liquid with a high dielectric constant to be pumped through the inner tube. As generic art, a radiator, i.e., a dielectric barrier discharge lamb, is known, for example, from JP laid-open specification HEI 2-7353 or U.S. Patent US-A-9 837 484, in which a discharge vessel is filled with a discharge gas forming "excimer" molecules and in which "excimer" molecules are formed by a dielectric barrier discharge, which is also designated as ozone production discharge or as silent discharge, as is described in "Discharge Handbook," Electrogesellschaft [Electric Company], June 1989, 7th Edition, page 263. In the radiator, light is radiated from the "excimer" molecules. In the above-named publications, an arrangement of a dielectric barrier discharge lamp is described, in which the discharge vessel has a cylindrical shape and functions at least partially also as dielectric of the above-described dielectric barrier discharge, which is at least partially transparent relative to the light radiated from the above-described "excimer" molecules. In this discharge lamp, further, the above-described light-transmitting dielectric is provided at least partially with netlike electrodes. Further, another design of a dielectric barrier discharge lamp is known, which has an approximately cylindrical outer shape as well as an overall hollow cylindrical discharge vessel, in which an external tube and an internal tube are arranged coaxially to one another, a discharge space exists between the external tube and the internal tube and a hollow space is formed inside the internal tube. The above-described dielectric barrier discharge lamps have various advantages, which neither conventional low-pressure mercury discharge lamps nor conventional high-pressure arc discharge lamps have, such as, for example, a radiation of ultraviolet rays with short waves, in which main wavelengths lie at 172 nm, 222 nm and 308 nm, and at the same time a selective production of light with individual wavelengths with a high efficiency, which are, for example, line-spectrum-like. However, it was regarded in this connection as disadvantageous that despite the lamp arrangement that is completely different from the conventional low-pressure mercury discharge lamp or the conventional high-pressure arc discharge lamp, no adequate examination of a coefficient of utilization of the light or of a maintenance of the lamp was performed. Such a dielectric barrier discharge lamp is used for reforming plastic surfaces, for forming layers or for similar purposes, and it is often used within an atmosphere in addition to air, such as, for example, within an atmosphere of nitrogen, argon, oxygen or the like. In this connection, however, it was regarded as disadvantageous that even though a dielectric barrier discharge lamp of hollow cylinder type allowed to linger in the air is introduced in a nitrogen atmosphere, air present inside the internal tube forming the hollow cylinder is emitted by steps in the nitrogen within a short time, without being substituted with the nitrogen, and without the nitrogen atmosphere being contaminated by the air. In this case, a suitability because of a high reliability is achieved, if the netlike electrodes arranged in the external tube are put on an earth potential and a high voltage is applied to the electrodes arranged in the internal tube. But in this case, it is regarded as disadvantageous that dust accumulates on the electrodes and that the accumulated dust precipitates as a mass on an object to be treated and contaminates it, since the electrodes, to which the high voltage is applied, have a dust-catching effect. The above-described drawbacks are characteristic for a dielectric barrier discharge lamp, which has a hollow cylindrical discharge space, which is designed so that an external tube as well as an internal tube with approximately cylindrical outer shapes are arranged coaxially to one another. These drawbacks occur especially when using the dielectric barrier discharge lamp for the purpose of a photochemical reaction. A first object of the invention therefore consists in indicating a dielectric barrier discharge lamp, which has a hollow cylindrical discharge space, which is designed so that an external tube as well as an internal tube with approximately cylindrical outer shapes are arranged coaxially to one another, and in which no contamination of a given atmosphere by air or the like for using the above-described discharge lamp occurs and thus a high reliability is achieved. A second object of the invention consists in indicating a dielectric barrier discharge lamp, which has a high light coefficient of utilization and at the same time a simple maintenance of the lamp. The first object is achieved according to the invention in that in a dielectric barrier discharge lamp, in which a discharge vessel with a hollow cylindrical discharge space, which is designed so that an external tube as well as an internal tube with approximately cylindrical outer shapes are arranged coaxially to one another, is filled with a discharge gas forming "excimer" molecules by a dielectric barrier discharge, in which an outer wall of the above-described external tube is at least partially transparent relative to the light radiated from the above-described "excimer" molecules and at the same time also functions as dielectric of the above-described dielectric barrier discharge, and in which the above-described light-transmitting dielectric is provided at least partially with electrodes, and further, according to the characterising portion of claim 1, in which a means for hermetic sealing of an interior of the above-described internal tube is arranged. The first object of the invention is further advantageously achieved in that the above-described means for hermetic sealing also functions as a holder of the above-described dielectric barrier discharge lamp, in that ceramic or resin is bonded to the above-described discharge vessel for the above-described means for hermetic sealing, in that a component that consists of a material that is approximately the same, such as the material of the internal tube, is applied in the above-described discharge vessel as precipitate (deposition) for the above-described means for hermetic sealing, or in that the above-described means for hermetic sealing consists of silicone rubber and hermetically seals the above-described internal tube. The first object of the invention is also achieved in that the means for hermetic sealing off of an end of the above-described internal tube is selected from the above-named means and at the same time identical means are used for hermetic sealing off of one and of the other end, or in that the interior of the above-described internal tube is hermetically sealed by filling the interior of the above-described internal tube with silicone rubber. Moreover, the first object of the invention is achieved in hat a hermetically sealed part is arranged at least on one end for the means for hermetic sealing of the above-described internal tube, in which a metal foil is inserted, by which (electrical) energy is fed to the above-described aluminum electrodes. The second object is achieved according to the invention in that in a dielectric barrier discharge lamp, in which a discharge vessel with an approximately cylindrical outer shape is filled with a discharge gas forming "excimer" molecules by a dielectric barrier discharge, in which an outer wall of the above-described discharge vessel is at least partially transparent relative to the light radiated from the above-described "excimer" molecules and at the Same also functions as dielectric of the above-described dielectric barrier discharge, and in which the above-described light-transmitting dielectric is provided at least partially with electrodes, at least on one end of the above-described discharge vessel, a holder is arranged whose outer diameter is less than/equal to an outer diameter of the above-described electrodes. Moreover, the second object of the invention is advantageously achieved in that the above-described holder consists of silicone rubber or fluororesin. By the arrangement for achieving the first object of the invention, the following advantages can be achieved: A contamination of the given atmosphere by another gas, such as air or the like, occurs only in a few cases, since the gas present inside the internal tube, such as air or the like, does not flow out toward the outside. A contamination of the object to be treated no longer occurs, since no more air flows on the electrodes, to which a high voltage was applied, and therefore no dust accumulates. The term "hermetic sealing" in the invention is to be understood to mean a hermetic sealing, which is not complete, like a vacuum resistance, but is a sealing by a usual inorganic adhesive or an adhesive based on silicone rubber to be able to prevent a flowing out of water. By the arrangement according to the invention, in which a component for the hermetic sealing of at least an inside of the above-described internal tube also functions as a holder of the above-described dielectric barrier discharge lamp, a light and at the same time reasonably-priced dielectric barrier discharge lamp can be obtained, since only a small amount of components is needed. Further, the advantage is obtained that the electrode leads, to which the high voltage is applied with a high frequency, can be tapped in a safe and simple way by the measure by which the means for hermetic sealing of at least one end of the above-described internal tube is arranged so that a material, in which one of the materials ceramic or resin or several of these materials is/are selected, is glued to the above-described discharge vessel, to hermetically seal the interior of the internal tube. According to the invention, a more compact hermetically sealed part and at the same time a high hermetically closing property are also achieved by the measure by which the internal tube is hermetically sealed so that a component, which consists of a material that is approximately the same, such as the material of the internal tube, is deposited in the above-described discharge vessel as deposition, and the flowing out of the gas, such as air or like, hardly occurs any more, if, for example, glass is deposited in the discharge vessel as deposition, if the discharge vessel consists of glass. Moreover, a simpler closing process can be achieved by the arrangement according to the invention, in which the above-described internal tube is hermetically sealed by a direct injection of the silicone rubber in an end of the above-described internal tube. In this connection, a reasonably-priced dielectric barrier discharge lamp with a good hermetic sealing property can be obtained at the same time, since the silicone rubber has good adhesive properties as well as ultraviolet radiation resistance. According to the invention, a largely simplified sealing process can furthermore, be achieved by the measure by which the means for hermetic sealing of an end of the above-described internal tube is selected from the above-named means and at the same time identical means can be used for hermetic sealing of one end and of another end, and an even more reasonably-priced dielectric barrier discharge lamp can be obtained. Further, a dielectric barrier discharge lamp with an even higher reliability can be obtained by the measure according to the invention in which the interior of the above-described internal tube is hermetically sealed by filling the entire space of the interior of the above-described internal tube with silicone rubber, since no more air is present inside the dielectric barrier discharge lamp and thus the problem of leakage in the hermetically sealed part no longer occurs. For the second object of the invention, the inventors have performed detailed tests with respect to a light coefficient of utilization of a conventional dielectric barrier discharge lamp and have discovered that the light coefficient of utilization is linked with a maintenance of the dielectric barrier discharge lamp and is influenced to a great extent especially by an arrangement of the holder arranged on the ends of the above-described lamp. The inventors have further discovered that the light coefficient of utilization decreases if an outer diameter of the holder is larger than the outer diameter of the above-described electrodes and that the reason for this lies in a distribution of light which is characteristic for a cylindrical dielectric barrier discharge lamp. Fig. 8 shows diagrammatically a light distribution. In the representation, a broken line designates a light distribution of a rod-shaped fluorescent lamp or halogen lamp. It is a circular curve 21 with a light output in a direction perpendicular to an axis of the lamp tube, i.e., in a direction in which, based on cosine , angle  = π/2 , as diameter. A solid line illustrates a light distribution of a dielectric barrier discharge lamp. It represents a curve 22, in which the light output in a range, in which  lies around 0 as well as π, is greater than the circular distribution. This means that in the dielectric barrier discharge lamp, the ratio of light, which is radiated in a direction adjacent to the axis of the lamp tube, is larger in comparison to a fluorescent lamp or the alike, and that therefore the light radiated in this direction is turned off by the holder and a reduction of a degree of light output, i.e., of the light coefficient of utilization, occurs if the outer diameter of the holder is greater than the outer diameter of the above-described electrodes. Such a phenomenon, that decreases because of an arrangement of the holders of the light output, i.e., the light coefficient of utilization, is a phenomenon typical of a cylindrical dielectric barrier discharge lamp. By the arrangement for achieving the second object of the invention, the above-described lamp can be incorporated in another component and positioned there without reducing the light coefficient of utilization and simultaneously in a simple and exact way. Moreover, because of an elasticity of this material, a simple incorporation in the ends of the discharge vessel is achieved by the measure in which the above-described holder consists of silicone rubber or fluororesin. In this connection, there is the further advantage that the leads connected to the electrodes can be tapped in a simple way. By the term "holder" in the invention, an arrangement is to be understood, which independently of the discharge vessel of the dielectric barrier discharge lamp is used to hold the lamp and is fastened to the discharge vessel by gluing with an adhesive or the like, by injection or the like. Further, the term "outer diameter of the above-described electrodes" in the invention is to be understood to mean an outer diameter of the netlike electrodes, which was measured in a state in which the electrodes were incorporated in the discharge vessel. According to the invention, the arrangement of the lamps may be such that as electrodes, seamless, cylindrical, netlike electrodes are arranged, which have a resilience in axial direction of the lamp, since the radius of the above-described netlike electrodes is reduced, comes to lie with the dielectric head to head, adjoining one another completely tightly, and thus no hollow space is formed in a part if the netlike electrodes are pulled in axial direction, after the discharge vessel was inserted in them. As a result, a production of harmful compounds in the area surrounding the lamp is prevented because of this unnecessary discharge and at the same time a stable discharge and thus a stable light output are obtained and the light yield is increased. This means that a dielectric barrier discharge lamp can be obtained, which has a space-uniform discharge, a stable discharge as well as a stable light output, since the above-described netlike electrodes on a surface of the approximately cylindrical dielectric have a sufficient uniformity, without an overlapping resulting, as in the formation of a suture line by bunching of the netlike electrodes. An outer diameter of the above-described electrodes can be calculated if a cylindrical netting produced by crossing litz wires with diameters of d mm is placed on a discharge vessel with a diameter of D mm, taking into consideration an "overlapping" of the litz wires by a sum of 4 x d and D. Brief Description of the Drawing Below, the invention is further described based on the embodiments represented in the drawing. There are shown in: Fig. 1 a diagrammatic representation of an embodiment of the dielectric barrier discharge lamp according to the invention; Fig. 2 a diagrammatic representation of an embodiment of the dielectric barrier discharge lamp according to the invention; Fig. 3 a diagrammatic representation of another embodiment of the dielectric barrier discharge lamp according to the invention; Fig. 4 a diagrammatic representation of still another embodiment of the dielectric barrier discharge lamp according to the invention; Fig. 5 a diagrammatic representation of still another embodiment of the dielectric barrier discharge lamp according to the invention; Fig. 6 a diagrammatic representation of still another embodiment of the dielectric barrier discharge lamp according to the invention; Fig. 7 a diagrammatic representation of netlike electrodes of the dielectric barrier discharge lamp according to the invention; and Fig. 8 a diagrammatic representation of a light distribution. Detailed Description First, embodiments for achieving the object of the invention are shown in Fig. 1: In the representation, a reference symbol 1 designates a discharge vessel, which is shaped like a hollow cylinder so that an internal tube 2 made of synthetic quartz glass and an external tube 3 made of synthetic quartz glass are arranged coaxially to one another. Discharge vessel 1 actually has, for example, a total length of about 150 mm, an outer diameter of the internal tube of 14 mm, an inner diameter of the external tube of about 25 mm as well as a thickness of 1 mm. On its outer surface, internal tube 2 has an aluminum electrode 5, which also functions as a light-reflector disk. A barium getter 6 is arranged on one end of discharge vessel 1. Electrode 5 is formed by cathode sputtering and has a thickness of, for example, 0.005 mm. External tube 3 also functions as a dielectric of a dielectric barrier discharge as well as as a light exit window and has a netlike electrode 4 on its outer surface. Netlike electrode 4, as partially illustrated in Fig. 7, is designed so that a metal wire 23 is made knitted seamless and cylindrical and loops are repeatedly made in peripheral direction 22a-22b of the cylinder. Metal wire 23 consists, for example, of monel with a litz wire diameter of 0.1 mm. A large mesh 24 and a small mesh 25 have an area of about 2 mm 2 and an area of about 1 mm 2 , respectively. Netlike electrode 4, which is arranged head to head tightly adjoining one another on an outer side of external tube 3, is designed so that discharge vessel 1 is inserted in this cylindrical metal netting and is pulled in axial direction of the lamp. By this arrangement, netlike electrode 4 is arranged on external tube. 3 head to head tightly adjoining one another. The cylindrical netlike electrode has an outer diameter of, for example, about 27.4 mm. For electrode 4, a conductive, netlike electrode is thus used in a suitable way. But it is also possible to design electrode 4 from a light-transmitting thin layer. Xenon gas is encapsulated as discharge gas with a pressure of, for example, 40 kPa (300 torrs) in in a discharge space 7 of discharge vessel 1. For example, in a discharge with an output of 2 W/cm lamp, by using a source of current 8 with a frequency of 20 kHz, ultraviolet rays with a wavelength of 172 nm and in the range of this wavelength were radiated with high efficiency. A gap of discharge space 7 lies, for example, at 5.5 mm. A holder 56 made of silicone rubber, provided with an air outlet orifice 55 is arranged on the two ends of discharge vessel 1. This holder 56 is placed on discharge vessel 1 by an adhesive based on silicone rubber, which is not represented in the drawing. A reference symbol 20 designates a protective film made of silicone rubber as an additional component for the purpose of mechanical and chemical protection of aluminum electrode 5. Since an outer diameter 57 of holder 56 is less than outer diameter 58 of cylindrical, netlike electrode 4, the above-described dielectric barrier discharge lamp's own light L, which is radiated in a direction adjacent to a tube axis of external tube 3 of discharge vessel 1, can be used effectively by the holder without interruption. Holder 56 can further be incorporated in another component in a simple and exact way, since it comprises a part with a smaller diameter 59. It has to be noted that the present application only claims dielectric barrier discharge lamps in which the interior 9 of the internal tube 2 is hermetically sealed. Moreover, there is the advantage that the placing of the holder on discharge vessel 1 can be performed in a simple way and at the same time, an adequate service life because of a sufficient resistance to the ultraviolet rays in a wavelength range of 172 nm as well as in the range of this wavelength can be obtained, since the holder consists of silicone rubber and thus has an elasticity. The same effect as in the above-described embodiment could also be obtained when using a holder made of fluororesin instead of silicone rubber. Further, by using a holder made of ceramic or metal, the light coefficient of utilization can be increased and the lamp can be positioned in a simple and exact way. Next, embodiments for achieving the first object of the invention are shown in Fig. 2: The same reference symbols as in Fig. 1 designate the same parts as in Fig. 1. A holder 60 made of aluminum oxide is placed on the two ends of discharge vessel 1 by means of an adhesive based on silicone rubber 63. An orifice is arranged in holder 60, orifice through which a line 64 goes, to which high voltage is applied. A gap between the orifice and line 64 is also hermetically sealed by the adhesive based on silicone rubber 63, and as a result, the line is also fastened at the same time. In this embodiment, the emission of air present on an inner side 9 does not occur by steps in the given atmosphere, such as nitrogen or the like, by the measure in which interior 9 of internal tube 2 is hermetically sealed by holder 60. The contamination of the nitrogen atmosphere by the air therefore does not occur either. According to the invention, a dielectric barrier discharge lamp with a high, reliability can furthermore be indicated, since no more air flows on electrode 5, to which the high voltage was applied, therefore no dust accumulates and no contamination of the object to be treated occurs. Fig. 3 illustrates another embodiment. Silicone rubber 70 was injected on the two inside ends of interior 9 of internal tube 2 of discharge vessel 1, and interior 9 of internal tube 2 was hermetically sealed. In this case, the advantage has been obtained that a sufficient service life is achieved, or advantages of this kind, since silicone rubber 70 has good adhesive properties, can be used at the same time in a simple way and has sufficient resistance to the ultraviolet rays with 172 nm and in the range of this wavelength. Also in this case, line 64 is fastened to a side of the high voltage and at the same time by means of silicone rubber 70. Fig. 4 shows still another embodiment. Silicone rubber 80 was injected in entire interior 9 of internal tube 2, and interior 9 of internal tube 2 was hermetically sealed. As a result, a dielectric barrier discharge lamp with an even higher reliability can be obtained, since no more air is present inside interior 9 and thus no more problem of leakage occurs in the hermetically sealed part. In Fig. 5, still another embodiment is illustrated. On one end on a side of getter 6 of discharge vessel 1, a wall 90 was formed by lengthening the glass forming discharge vessel 1 and was hermetically sealed. This means that glass wall 90 in discharge vessel 1 was applied as deposition. A holder 91 made of silicone rubber was placed by means of an adhesive based on silicone rubber 93 on another end of discharge vessel 1. In this embodiment, there is the advantage that a simpler arrangement can be obtained. Fig. 6 shows diagrammatically still another embodiment. An end 71 of internal tube 2 is closed. A side of internal tube 2, which comes in contact with interior 9, is provided with two groovelike mirrors 95 made of aluminum, so that a cylindrical aluminum mirror is arranged as a whole. Another end 72 of internal tube 2 is a hermetically sealed part, in which a molybdenum metal foil 73 is inserted, from which an outside connection 74 extends outward and an inside connection 75 extends inward. Inside connection 75 is connected to above-described aluminum mirror 95. A power supply for aluminum mirror 95 can therefore be made coming from outside connection 74. This means that mirror 95 also has the function of an electrode. Both ends 76 of external tube 3 are fused with internal tube 2. A reference symbol 77 designates a residual part of an air outlet tube, which was used in a filling process of the nitrogen gas after evacuation of interior 9 of internal tube 2. Aluminum mirror 95 is therefore protected by an inactive gas, such as nitrogen. A reference symbol 78 designates a residual part of an air outlet tube, which was used in a filling process of a gas, necessary for the discharge, after evacuating discharge space 7 between internal tube 2 and external tube 3. In this embodiment, the, advantage is that the lamp can be produced in a very simple way. As described above, the contamination of the given atmosphere by air or the like for using the lamp can be prevented according to the invention. Further, a sufficient light coefficient of utilization and at the same time simple maintenance of the lamp can be achieved according to the invention.

Claims: Dielectric barrier discharge lamp, in which a discharge vessel (1) with a hollow cylindrical discharge space (7), which is designed so that an external tube (3) as well as an internal tube (2) with approximately cylindrical outer shapes are arranged coaxially to one another, is filled with a discharge gas forming "excimer" molecules by a dielectric barrier discharge, in which an outer wall of the external tube (3) is at least partially transparent relative to the light radiated from the "excimer" molecules and at the same time also functions as a dielectric of the dielectric barrier discharge, and in which the light-transmitting dielectric is provided at least partially with electrodes (4, 5), characterised in that a means (60, 61, 70, 71, 72, 80, 90, 91) for hermetic sealing of an interior (9) of the internal tube (2) is arranged. Dielectric barrier discharge lamp according to claim 1, wherein the means for hermetic sealing is also used as a holder (60, 91) of the dielectric barrier discharge lamp. Dielectric barrier discharge lamp according to claim 1, wherein the means for hermetic sealing consists of a material which is selected from ceramic or resin or several of these materials, and wherein this means is bonded (63, 93) to the discharge vessel (1). Dielectric barrier discharge lamp according to claim 1, wherein for the means for hermetic sealing (90), a component which consists of a material that is approximately the same as the material of the internal tube (2) is deposited in the discharge vessel (1) as deposition. Dielectric barrier discharge lamp according to claim 1, wherein the means for hermetic sealing consists of silicone rubber. Dielectric barrier discharge lamp according to claim 1, wherein identical means (70) are used for hermetic sealing off of one end and of the other end of the internal tube (2). Dielectric barrier discharge lamp according to claim 1, wherein the means for hermetic sealing (80) of an interior (9) of the internal tube (2) is silicone rubber, with which the interior of the internal tube (2) is filled. Dielectric barrier discharge lamp according to claim 1, wherein an electrode (5) is arranged on the interior (9) of the internal tube (2), to which a high voltage is applied, and wherein another electrode is grounded. Dielectric barrier discharge lamp according to claim 1, wherein an electrode lead (64) is arranged, which is connected to the electrodes (4, 5), and wherein this electrode lead is fastened in the hermetically sealed part (9). Dielectric barrier discharge lamp according to claim 1, wherein an aluminium electrode (95) is arranged inside the internal tube (2), which functions also as a mirror, and wherein at the same time in hermetic sealing of the interior (9) of the internal tube (2), a hermetically sealed part (72) is arranged, in which a metal foil (73) is inserted at least on one end, by which the aluminium electrode (95) is fed energy. Dielectric barrier discharge lamp according to any one of the preceding claims, wherein the electrodes consist of a seamless, cylindrical, conductive netting (4), which has resilience in the axial direction of the above-described discharge lamp. Dielectric barrier discharge lamp according to any one of the preceding claims, wherein at least on one end of the discharge vessel (1), a holder (56) is arranged, whose outer diameter (57) is less than/equal to an outer diameter (58) of the electrodes (4). Dielectric barrier discharge lamp according to claim 1, wherein the holder (60,91) consists of silicone rubber or fluororesin.

Inventors: ASAHINA TAKASHI, HIRAMOTO TATSUMI, HISHINUMA NOBUYUKI, IGARASHI TATSUSHI, KASAGI KUNIO, MATSUNO HIROMITSU, OONISHI YASUO, TAKEMOTO FUMITOSHI, WAKAHATA YASUHIKO, ASAHINA, TAKASHI, HIRAMOTO, TATSUMI, HISHINUMA, NOBUYUKI, IGARASHI, TATSUSHI, KASAGI, KUNIO, MATSUNO, HIROMITSU, OONISHI, YASUO, TAKEMOTO, FUMITOSHI, WAKAHATA, YASUHIKO
Applicants: USHIO ELECTRIC INC, USHIODENKI KABUSHIKI KAISHA
Application year: 1994
Main classification: H01J65
IPC codes: H01J65